Synthesis and characterization of CrB2 thin films grown by DC magnetron sputtering
Megan Mahrokh Dorri, Jimmy Thörnberg, Niklas Hellgren, Justinas Pališaitis, Andrejs Petruhins, Fedor F. Klimashin, Lars Hultman, I. Petrov, Per O. Å. Persson, Johanna Rosén
Abstract
CrBx thin films with 1.90 ≤ x ≤ 2.08 have been deposited by direct-current magnetron sputtering (DCMS) from a stoichiometric CrB2 target at 5 and 20 mTorr (0.67 and 2.67 Pa) Ar pressure onto sapphire (0001) substrates. All films, irrespective of deposition conditions, exhibit a (0001) texture. Attesting to the achievement of close-to-stoichiometric composition, epitaxial film growth is observed at 900°C, while film growth at 500 °C yields (0001) fiber texture. Film composition does not depend on substrate temperature but exhibits slightly reduced B content with increasing pressure for samples deposited at 900°C. Excess B in the overstoichiometric epitaxial CrB2.08 films segregates to form B-rich inclusions. Understoichiometry in CrB1.90 films is accommodated by Cr-rich stacking faults on {11¯00} prismatic planes.